"I turn souls inside out," observes the psychiatrist to the artist who is grimly striving to avoid him, "and what do I see? But you'd know, of course—you and your self-portraits." The only reply he gets is a punch on the nose (which, scientific detachment being what it is, he later returns with interest when his assailant is safely outnumbered). But his point—and Bergman's—is stingingly accurate. Like psychiatrists, artists can only work on the basis of what is inside themselves, and the truths that they uncover are as much personal as general. What amuses Bergman, however, is that the array of truth in his self-portraits is so complex and elusive that his would-be analysts can lose even themselves in the attempt to ferret them out.

As with Persona, he challenges us in Hour of the Wolf (United Artists) to detect what is real in an indigenously unreal situation, and absolves himself from any responsibility towards providing a solution by confronting us at the conclusion as at the beginning with Liv Ullmann's appealing expression of contrite and inarticulate bewilderment. Bergman has always been at pains to establish that within the arch of his own proscenium anything can happen, and that when it does it will be, in several senses, his own affair. His method might be a game of charades, a cartoon on an ancient projector, a circus act, a medieval roadshow, an opening and closing on flaring carbons, but there has rarely been a Bergman film without at some point a miniature curtain being raised to reveal posturing souls in torment. The purpose is two-fold: on the one hand to remind his audience that even a one-act play requires a deus ex machina, on the other to stress that just as words are inadequate communication symbols for pure thought, so drama is merely an attempt to formulate for easier comprehension concepts normally too abstract to be defined.

Films and theatre cannot help but allegorize, for they involve contrivance and artificiality; but the joke, as Bergman sees it, is that through artifice they are nevertheless capable of getting closer to reality than any other medium. The joke is better still when that reality turns out to be nebulous or, like the logic of Aquinas, perversely illogical. For all that the artist may proclaim the unimportance of his work in the world of man, it is only through that work that the world can be revealed, an endless paradox.

So Bergman turns Hour of the Wolf into a succession of deceptive curtain-raisings, each leading us into deeper darkness until, like the exhausted couple keeping each other awake until dawn, we can conjure demons out of nothing. To start, the Bergman proscenium. Behind simple credits, the racket of stagehands at work, dwindling to a hush as the scene is set. Added alienation and insulation, as a narrator (Bergman himself?) puts the whole thing on the level of a dry report; then, as yet another complication, Alma Borg gives her version of the circumstances of her husband's disappearance.

Not until the flashbacks do we eventually come to grips with what appear to be the basic facts, and these in turn convey a speedy unreliability. Did Alma really receive a visit from an old lady in white whose hand she might have held and whose words were sometimes lost in the roar of the sea, or did she invent her (based on a fantastic sketch by her husband) to conceal her guilty intrusion into the secrets of Johann's diary? Worse, although we can assume that her recollection of the diary entries is accurate, does the diary itself report truths or inventions, genuine or imagined hallucinations? One can prowl through Hour of the Wolf with pedantic schematism and deduce from the evidence provided by husband or wife or both (and taking roughly into account the stages of their mental disintegration) what is "real" (all their scenes together), what is distorted "reality" (most of the scenes at the castle), and what is totally "unreal" (for the sake of argument, all scenes described only in Johann's diary plus the murder of the boy)—although whichever way one interlocks the jigsaw there are awkward pieces (the assault on Heerbrand, the arrival of the gun, and the final scene of Johann's disappearance).

But to sift through the film in this way is to imply that parts of it can be disregarded or discarded altogether in favour of a tidy narrative of psychopathic degeneration. They can't. Hour of the Wolf contrives to be another step forward on the path that could imaginably, and honourably, have reached its destination with Persona; and it does so both by approaching the Persona argument from an entirely new (and healthily sardonic) tangent, and by enriching it with several layers of illustration. The richest, perhaps Bergman's richest yet, is the link with "The Magic Flute." Controlled by the satanic impresario Lindhorst (on whose face a shadow flings a clown's smile), yet another curtain rises, to reveal Tamino with the song of mingled despair and hope (O ew'ge Nacht) that is at the same time a hymn to a love worth seeking and an apology for unfamiliarity with the rules of Freemasonry (representing, one might interpret, the established society from which Johann is an outcast).

It's a hefty clue, and there's a case to be made for relating everyone from Bergman downwards to the dying Mozart and his chameleon-like characters, whether or not one can strain this further than the astonishing scene in which Lindhorst/Papageno conducts Johann/Tamino along a corridor thick with wings to the room of Veronica/Pamina. "You see what you want to see," calls the Bird Man, feathers and all. However, the subsequent destruction of Johann by his jealous admirers, who having laughed him to scorn proceed to tear him to bits (they have, after all, found his replacement already in the pallid form of Kapellmeister Kreisler), is hardly vintage Mozart so much as undiluted contemporary Bergman, for whom critics were ever a fickle bunch...

Twenty-two years ago (Crisis) Bergman was telling the story of a man tom between two women; ten years ago (The Face) he was showing a performer being stripped of his mask, and five years ago (The Silence) he was revealing a single human coin by the examination of both its sides. All these were present in Persona, and they recur again in Hour of the Wolf, augmented on the immediate visual level by such familiar Bergman phrases as the bleached flashback (Sawdust and Tinsel), the errant eyeball (The Face), and the corpse that rises laughing from its slab (Wild Strawberries).

Yet there are new departures, too—the dizzying revolve by Nykvist's camera around the dinner-table, the hideous ambivalence of the murder scene, the startling levitation of the Baron (a joke that is delicately capped by von Sydow's nervous glance at the ceiling as he hurries on his way), the jump-cuts with the firing of the gun, the rapturous Lester-style burst of sunlight on the lens as Veronica flings herself into her lover's arms. "Awful things can happen," she murmurs. "Dreams can be revealed." Nightmares as well, it seems. In the hour before dawn, Bergman's imagination remains the finest, and the most disturbing, of all the cinema's modem visionaries.